I would use a paint/coating for real steel guns like duracoat, cerakote, or alumahyde. Tons better than regular spray paint. Looks more legit and is more durable. Something with a few steps or with baking time will be better for sure.
I'm also interested in plastidip spray. They have metallic sprays now that might be pretty cool. And if you don't like it, you just peel it off. I did my loader in plastidip camo tan and it's held up alright.